Sensor arrays : an inspired idea or an objective measurement of environmental odours ?

The measure of annoyance odours from sewage treatment, landfill and agricultural practise has
become highly significant in the control and prevention of odorous emissions from existing
facilities and is crucial for new planning applications. Current methods (such as GC-MS analysis,
H2S and NH3 measurements) provide an accurate description of chemical compositions or act as
surrogates for odour strength, but tell us very little about the perceived effect, whereas
olfactometry gives the right human response but is very subjectivity and expensive. The use of
non-specific sensor arrays may offer an objective and on-line instrument for assessing olfactive
annoyance. Results have shown that sensor array systems can discriminate between different
odour sources (wastewater, livestock and landfill). The response patterns from these sources can be significantly different and that the intensity of sensor responses is proportional to the
concentration of the volatiles. The correlation of the sensors responses against odour strengths
have also shown that reasonable fits can be obtained for a range of odour concentrations (100 -
800,000 ou/m3). However, the influence of environmental fluctuations (humidity and temperature) on sensor baselines still remains an obstacle, as well as the need for periodic calibration of the sensory system and the choice of a suitable gas for different environmental odours.